The present invention relates to an optical processing apparatus that processes a workpiece with laser.
A conventional optical processing apparatus shown in FIG. 2 converges light emitted by semiconductor laser 101 which converts electrical energy into optical energy (electric circuit is not illustrated here), and irradiates the light to workpiece 111. In an optical processing apparatus used for manufacturing processes, radiating faceplate 102 of semiconductor laser 101 and a group of lenses 105 that compose an optical convergence system are provided on their surfaces with special surface treatment for antireflection of the light in order to effectively use the optical energy generated. Respective surfaces of radiating faceplate 102 of the semiconductor laser 101 and the group of lenses 105 are damaged if getting wet with waterdrops due to, e.g., dew formation, thereby preventing the apparatus from producing a sufficient output.
To prevent such a problem, the conventional processing apparatus is equipped with desiccant 113 within hermetically-sealed interior space 103 accommodating the semiconductor laser 101 and the group of lenses 105. Desiccant 113 prevents contaminant such as waterdrops from adhering to the surface of radiating faceplate 102 of the semiconductor laser 101.
Shielding gas 110 needs to be supplied into in-process area 112 of workpiece III to protect it from surrounding air when the converged light is used for processing such as welding. For this reason, shielding gas 110 is supplied usually with side nozzle 108 mounted to a position at an angle different from that of the optical processing apparatus.
Semiconductor laser 101 and the group of lenses 105 represent major heat-generating elements. For the semiconductor laser 101, in particular, a water-cooling structure is mainly used, while thermo-electric cooling system using the Peltier effect may be employed as another method in certain instances. In the group of lenses 105, if a large temperature change occurs during the processing in enclosure 104 holding the lenses, the change influences positional accuracy as well as optical accuracy of the group of lenses 105 for converging the light, thus causing a change in the convergent characteristic, that is, performance of the processing. A processing apparatus may include a part of group of lenses 105 water-cooled for this reason.
The group of lenses 105 is provided with cover glass 107 for protecting them from contaminant gases such as fumes, emanating particles such as dust generated during the processing from in-process area 112 of the workpiece 111.
The conventional optical processing apparatus has a complex structure to accommodate the semiconductor laser 101 and the group of lenses 105, since employing the conventional method of preventing moisture and dust, which requires an increase in hermeticity of interior space 103. The processing apparatus also requires a complicated procedure to handle, as it needs periodical change of the desiccant 113.
Moreover, a vortex of surrounding air, which may result in improper shielding of the in-process area 112, may be generated depending on mounting angle xcex8 of side nozzle 108 for supplying shielding gas 110 to protect in-process area 112 of the workpiece 111 from the surrounding air, a distance d from in-process area 112, and inclination angle xcex3 of side nozzle 108 with respect to direction X of the processing.
The optical processing apparatus is provided with a water-cooling structure mainly for the semiconductor laser 101, in order to reduce temperature during the processing. Even with other cooling methods, a temperature gradient may increase between a cooled end and a heat source within the semiconductor laser 101 if a temperature of interior space 103 rises, which leads to an increase in temperature of the heat source, i.e. a light-generating section. This affects an operational life of the semiconductor laser 101.
In addition, it is difficult to cool the entire group of lenses 105 due to problems relative to water-cooling of the group of lenses 105, such as difficulty in ensuring water-tightness, complexity of the structure, increase in processing cost associated with these problems. Accordingly, there has been a limitation in maintaining the processing performance stable. Furthermore, cover glass 107 is liable to being stained quickly as being exposed directly to contaminant gas and emanating particles. This requires cover glass 107 to be replaced promptly in order to be prevented from degradation of the processing performance, thereby giving rise to a problem in work-hours and cost.
An optical processing apparatus which is easily handled and has an outstanding processing performance is provided.
The optical processing apparatus includes a laser source, an enclosure which accommodates the laser source and having an inlet opening for introducing gas and an outlet opening for discharging the gas, a lens disposed to a path of laser irradiated from the laser source, a lens holder for supporting the lens, and a cylinder covering an exterior of the lens holder to form a space with the lens holder for guiding the gas to flow through the space.